HPTN 056

Characterization of Baseline Mucosal Indices of Injury and Inflammation in Men for Use in Rectal Microbicide Trials

Study Summary
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What was HPTN 056?

An observational study with endoscopic collection of distal colonic and rectal tissue biopsies over a 6-week period to identify mucosal indices that would be valuable in the safety evaluation of rectal microbicides and to determine the sensitivity and variability of those assays.

Who participated in the study?

HIV infected and uninfected men who have sex with men (MSM) aged 18-50 years old.

What happened during the study?

Sixteen male participants were enrolled into 4 groups defined by HIV status, viral load, and sexual activity. Each participant underwent 3 flexible sigmoidoscopies at 2-week intervals with collection of blood, intestinal biopsies, and rectal secretions.


Qualitative histology demonstrated minimal inflammation in >95% of biopsies and remained stable throughout the study period. ICC for the tissue cytokine mRNA measurements and several T-cell phenotypic markers was >0.7, indicating stability over time. Mucosal CD4 lymphopenia was seen in the HIV-positive participants and was more pronounced in those with higher viral loads.

Why was this study important?

The development of new rectal microbicides involve defining the safety and efficacy profile of each agent – safety had to be measured in order to create an effective microbicide.

Study Documents